<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="style.css">
    <style>
        .header{
            width:100%;
            height:60px; background: pink;
        }
        .main,body,html{
            height:100%;
        }
        .left-side{
            width:200px;
            height:100%;
            background: red;
            float: left;
        }
        .right-side{
        
            /* width:calc(100% - 200px); */
            width:100%;
            height:100%; background: yellow;
           
        }
    </style>
</head>
<body>
    <div class="header"></div>
    <div class="main">
        <div class="left-side">左边</div>
        <div class="right-side">右边</div>
    </div>
</body>
</html>